Hi @ams1511 and everyone (smile)
Ams1511 what you are observing is a normal behavior...what you have exported to AutoCAD is the viewport (that is the Frame you currently see in your AutoCAD Image... When you Export a "Sheet" the Frame of the VIEWPORT which includes7encloses all elements showing on that sheet End to End is what will show in AutoCAD (the purple frame on the rightside Image below)...ie: in this case it is determined by the extents of the Level Datums on your sections in Revit. See Image below
- marked by a red arrow (left - Revit): Viewport Frame
- marked by a blue arrow (left - Revit): : Crop Region

If you resize the crop Region in the related views and/or the Annotation crop it will still Export the same current Frame you have as Long as the Level Datum remains as is (ie: extending outside the crop Region)...If you want to resize that Frame to match the actual Crop Region of the related view in Revit you need to (in Revit) go to the related view(s); select and drag the Level Datums to fit them inside the crop region. In such case the Crop Region would be the the actual extent of all elements included in the view (including the Datums) => + or - the viewport
An alternative method is NOT to Export the Viewport category and replace those Frame with a Frame modeled using a Generic Annotation Family or a Details line Family.
As far as I know; the default Crop Region of the Revit view itself will not be exported regradless if it is on a sheet or not on a sheet...I have neither seen this exproted before nor have I ever found Export/Layer Settings for Crop Regions. It is true that there is an article somewhere on the Autodesk Knowledge Network that Claims that CR are exported if placed on Sheets but the Images found in that article do not Support that Claim...it is the viewport extents ...
If anyone knows where that layer setting for crop regions is and/or under which category I would love to hear : o) always open for new ideas
(PS: Crop Regions are not under any category and they are one of those elements in Revit whose visibility can only be overrriden by element)